Stable Hydrogen Production Research Articles

Coprecipitation dispersion of Cu-Zn-Zr mixed oxides nanocatalyst over Si and Al-Based supports applied in selective and stable hydrogen production from Methanol: Experimental study and rate of reaction engineering via intelligent optimization of CFD method

This study focused on evaluating different support materials made of silicon (Si) and aluminum (Al) for improving the properties of catalysts and their ability to produce high-purity hydrogen from methanol. Accordingly, four coprecipitation-supported nano-scale CuO/ZnO/ZrO2 catalysts were fabricated. Accordingly, MCM-41, γ-Al2O3, and activated alumina materials were used as supports for these catalysts. Various methods such as BET, EDX, FESEM, FTIR, PSD, and XRD were used to analyze the prepared catalysts. The results of FESEM and EDX indicated that using activated alumina as a support led to the smallest copper particle size and excellent dispersion on its surface, and prevented the agglomeration of particles. The catalyst made with activated alumina also had the largest surface area, which is beneficial for reactions. This catalyst showed strong methanol conversion ability and produced less undesirable CO during hydrogen production from methanol. Additionally, a stability test lasting 1220 min confirmed that this catalyst maintained consistent performance over time. A novel method combining CFD and genetic optimization algorithms was used to synthesize new catalysts for catalytic steam reforming of methanol. This approach accurately estimated reaction rates and activation energies, achieving an RMSE below 0.01 for all outcomes. The optimal catalyst, CZZ-Al2O3 (A), exhibited activation energies of 73.928 J/mol, 71.261 J/mol, 106.516 J/mol, and 143.217 J/mol with an RMSE of 0.0089.

Enhanced morphological maintenance and redox stability by dispersing nickel ferrite into silica matrix for chemical looping hydrogen production via water splitting

Chemical looping hydrogen production (CLHP) is widely regarded as a clean and efficient route for high purity hydrogen production. However, a huge barrier is how to avoid serious deactivation caused by sintering and agglomeration of oxygen carriers. A novel fabrication process of highly dispersing NiFe2O4 into silica matrix is proposed. The oxygen carriers of NiFe2O4 completely dispersed over silica matrix (NFSM) are successfully synthesized. The characterizations, hydrogen production capacity and cycle redox performance of oxygen carriers are further investigated. The results illustrate that NiFe2O4 active components are homogeneously dispersed on the silica matrix without any impurities. NFSM demonstrates the highest reactivity with CO as well as the greatest hydrogen production of 296 mL/g due to the strong confinement effect of silica matrix and good particle dispersion. The porous silica matrix offers large amounts of channels for the lattice oxygen transport and effectively prevents Fe and Ni cations outward migration to particle surface, which actually inhibits the larger clusters and sintering. NFSM can keep stable hydrogen production of approximately 290 mL/g during the cyclic experiments. Briefly, the innovation method of embedding active component into well-established silica matrix supports contributes to the enhanced anti-sintering properties and redox stability of oxygen carriers.

Electron Regulation of Heterostructured Pt/Rh Metallene Boosts Ethylene Glycol Electrooxidation and Hydrogen Evolution.

The research on high-efficiency two-dimensional (2D) catalytic materials for the small-molecule oxidation-assisted hydrogen evolution reaction (HER) is prospective for efficient hydrogen production. Herein, we report heterostructured Pt/Rh metallene with Pt nanoparticles (NPs) uniformly anchored on Rh metallene for the HER and ethylene glycol oxidation reaction (EGOR). The ultrathin sheet structure of the Pt/Rh metallene offers high surface areas and sufficient active sites. More importantly, the Pt/Rh heterostructure can optimize catalytic active centers and adjust electronic structure. Thus, Pt/Rh metallene exhibits superior electrocatalytic HER activity with a low overpotential of 28 mV in 1 M KOH at 10 mA cm-2 and EGOR activity with a specific activity of 8.39 mA cm-2 in 1 M KOH with 3 M EG, along with outstanding CO tolerance. In a two-electrode system, Pt/Rh metallene requires a low potential of 0.51 V for stable and efficient hydrogen production at 10 mA cm-2 in 1 M KOH + 3 M EG, with the simultaneous production of high-value-added products. The job proposes an attractive strategy for the synthesis of 0D/2D metallene toward simultaneous energy-saving hydrogen production and chemical update.

Improving the power quality and hydrogen production from renewable energy sources based microgrid

The world is looking for utilization of renewable energy sources to reduce global warming as well as the consumption of fossil fuels. In this scenario, solar and wind energy are widely used at many places worldwide. However, both solar irradiance and wind speed are depending on nature. Hence, an energy storage device must be required to operate at their best utilization level by converting them to electricity. One of the best energy storage devices for medium power range is the battery. However, batteries require high maintenance and suffering from self-discharge as well as storage capacity will be decreased day by day. Hence, storing hydrogen can be an economically feasible solution instead of using batteries for high power range. Usually an aqua electrolyzer can easily convert water to hydrogen and oxygen through electricity. However, due to slow dynamics of heat transfer from electricity, the generation of hydrogen cannot meet the fast response like electrical devices. Therefore, a novel controlling technique is required to increase the production quality of hydrogen during random changes in both solar irradiance and wind speed. In order to achieve the best utilization, both photovoltaic panels and wind turbines are operated at their maximum power point levels. In this research boost converters are used to operate as maximum power point tracking devices. The whale optimization technique is integrated to respective controllers of all the converters to achieve stable production of hydrogen during rapid changes in irradiance and wind speed. The Whale Optimization Algorithm (WOA) technique is compared with Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Grey Wolf Optimization (GWO) to show the benefits of tracking response of the system on improving production of hydrogen from hybrid renewable energy sources based Microgrid. Hardware—in the—Loop (HIL) is developed to analyze the results with the help of OPAL-RT modules. Along with HIL results, a Real Time Digital Simulator (RTDS) based results are also presented to evaluate the performance of the proposed method.

One-pot synthesized Li, V co-doped Ni3S2 nanorod arrays as a bifunctional electrocatalyst for industrialization-facile hydrogen production via alkaline exchange membrane water electrolysis

The design of a bifunctional electrocatalyst with excellent performance in water electrolysis under high current densities for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with non-noble metals-based catalysts has been challenging. A novel bifunctional electrocatalyst constituted as the lithium and vanadium (Li, V) co-doped nickel sulfide (Ni3S2) nanorod arrays (LVN-0.1) is designed and investigated to take this challenge. The overall water splitting (OWS) electrolyzer constructed with our LVN-0.1 catalyst exhibited low cell voltages of 1.44 and 1.95 V to achieve 10 and 1000 mA/cm2, respectively, with excellent durability, which is almost the best Ni3S2-based electrocatalyst reported to date. The practical scale-up LVN-0.1 stack cell of 2 × 2 cm2 required 1.92 and 2.02 V to achieve high current densities at the industrial level at 500 and 1000 mA/cm2, respectively. Notably, our alkaline stack cell achieved a cell-efficiency of 61.9% and cell stability for 200 h at 1000 mA/cm2, while commercial alkaline cells have kept operating below 500 mA/cm2 to avoid the drop-off of binder-coated electrocatalysts. This study provides a facile way to design bifunctional electrocatalysts for realizing high efficient and stable hydrogen production by alkaline water splitting.

Hydrogen production by isothermal thermochemical cycles using La0.8Ca0.2MeO3±δ (Me = Co, Ni, Fe and Cu) perovskites

Solar-driven thermochemical water splitting has the potential to transform concentrated solar energy into green hydrogen and other solar fuels. In this work, La0.8Ca0.2MeO3±δ (Me = Co, Ni, Fe and Cu) perovskites have been synthesised by a modified Pechini method and evaluated as materials for hydrogen production by two step thermochemical water splitting cycles. Performing the thermal reduction at temperatures of 1200 and 1000 °C, while the oxidation is done at 800 °C, allows a remarkable and stable hydrogen production after 5 consecutive cycles. However, the perovskites suffer changes in the structure after each redox cycle, with potential effects in the long-term cyclic operation. On the contrary, the isothermal thermochemical cycles at 800 °C produce a stable amount of hydrogen with each consecutive cycle maintaining the perovskite structure. This hydrogen production ranges from 3.60 cm3 STP/gmaterial·cycle for the material with the lowest productivity (La0.8Ca0.2FeO3±δ) to 5.02 cm3 STP/gmaterial·cycle for the one with the highest activity (La0.8Ca0.2NiO3±δ). Particularly the Ni-based material shows the highest H2 productivity accompanied by very good material stability after 15 consecutive cycles, being possible to combine with current solar thermal facilities based on concentrated solar power technologies like plants with central receivers.

Optimal integration of electrolysis, gasification and reforming for stable hydrogen production

Engineering industries such as petroleum and petrochemicals have strict requirements for the stability of hydrogen supply to ensure the safety and reliability of system operations. However, relying on a single hydrogen production technology is insufficient to meet the requirements of both stable and green hydrogen. This study proposes an integrated hydrogen production system combining water electrolysis, biomass gasification, and natural gas reforming to achieve stable and green hydrogen. To capitalise on the advantages of the individual technologies, the integration among the different hydrogen production methods considers not only energy but also materials. As a by-product of water electrolysis, oxygen can create a pure oxygen atmosphere for biomass gasification and natural gas reforming, thereby considerably improving the energy conversion rate. The heated gases from the biomass gasification transport thermal energy to the natural gas reforming. Stable and maximised hydrogen production can be achieved through optimal coordination of the three hydrogen production technologies and storage devices. Optimisation models are built for each component, and case studies show that the proposed integrated system exhibits energy efficiency of 64.19 %, which is 9.87 % higher than the 54.32 % efficiency of single-energy hydrogen production, and achieves an 67 % carbon emission reduction compared with the existing industrial technology. The integrated system proposed in this study provides a solution for stable hydrogen production under the broad requirement of carbon neutrality, and it will provide valuable guidance for future integrated hydrogen production system development and offer information that is of interest to operators and investors.

Synergistic integration of MXene nanosheets with CdS@TiO2 core@shell S-scheme photocatalyst for augmented hydrogen generation

In order to ensure continuous and stable production of hydrogen (H2), the development of hierarchical nanostructures within a few-layer Mxene nanosheet, incorporating an ultrathin TiO2 shell material, is essential. This shell material plays a crucial role in maintaining the long-term stability of the core and preventing photo-corrosion, thus enabling uninterrupted H2 generation. To evaluate their potential as visible-driven photocatalysts for high H2 production, we conducted a comparative analysis of CdS cores covered with three different shell transition metal oxides (TiO2@NiO@ZnO), supported by Mxene. Structural and morphological characterizations through XRD and TEM confirmed the formation of pure CdS@TiO2@NiO@ZnO core–shell nanostructures, characterized by spherical shapes with a core diameter of 187 nm and a shell thickness of 19.2 nm. XPS experiments demonstrated the structural integrity of the individual elements within the nanocomposite, existing in their respective oxidation states within the core@shell structure. The hierarchical nanostructure exhibited optical characteristics with an absorption edge ranging from 480 to 580 nm. Among the three different shell materials, TiO2 displayed the highest photocatalytic activity under visible light irradiation, followed by NiO and ZnO. Based on our findings, the CdS@TiO2 core@shell photocatalyst supported by Mxene exhibited the highest efficiency, with a production rate of 16.2 mmol.h−1.g-1cat. This can be attributed to enhanced charge separation, the spatial distribution of carriers, and favorable structural properties. Our DFT calculations further supported the efficacy of coupling Mxene with CdS/TiO2, as it facilitated efficient water splitting, with CdS favoring H2O dissociation and Mxene favoring HER. These results highlight the potential of developing highly efficient photocatalysts for water splitting by integrating Mxene with CdS/TiO2. Additionally, The prepared CDTM (Mxene@CdS/TiO2) photocatalyst existing S-scheme heterojunction for efficient water splitting. This underscores the system's effective functioning across diverse sceneries, Overall, our study presents a feasible and effective strategy for constructing an S-scheme heterojunction system that utilizes photo charge carrier separation to enhance the utilization and conversion of solar energy.

Catalytic Steam-Reforming of Glycerol over LDHs-Derived Ni-Al Nanosheet Array Catalysts for Stable Hydrogen Production

In the present work, LDHs–derived Ni–Al nanosheet arrays (NiAl/NA) were successfully synthesized via a one–step hydrothermal method, and applied in the steam-reforming of glycerol reaction for enhanced and stable hydrogen production. The physicochemical properties of catalysts were characterized using various techniques, including XRD, SEM–EDS, XPS, N2–physisorption, Raman, and TG–DTG. The results indicate that smooth and cross–linked Ni–Al mixed metal oxide nanosheets were orderly and perpendicularly grown on the Ni foam substrate. The SEM line scan characterization reveals the metal concentration gradient from the bottom to the top of nanosheet, which leads to distinctly optimized Ni valence states and an optimized binding strength to oxygen species. Owing to the improved reducibility and more exposed active sites afforded by its array structures, the NiAl/NA catalyst shows enhanced glycerol conversion (83.1%) and a higher H2 yield (85.4%), as well as longer stability (1000 min), compared to the traditional Ni–Al nanosheet powder. According to the characterization results of spent catalysts and to density functional theory (DFT) calculations, coke deposition is effectively suppressed via array construction, with only 1.25 wt.% of amorphous carbons formed on NiAl/NA catalyst via CO disproportionation.

Long-Term Stable Hydrogen Production from Water and Lactic Acid via Visible-Light-Driven Photocatalysis in a Porous Microreactor.

Photocatalytic hydrogen (H2) production is significant to overcome challenges like fossil fuel depletion and carbon dioxide emission, but its efficiency is still far below commercialization need. Herein we achieve long-term stable H2 bubbling production from water (H2O) and lactic acid via visible-light-driven photocatalysis in a porous microreactor (PP12) benefit for photocatalyst dispersion, charge separation, mass transfer and dissociation of O-H bonds of H2O. With the widely used platinum/cadmium-sulfide (Pt/CdS) as photocatalyst, PP12 leads to a H2 bubbling production rate of 602.5 mmol h-1 m-2, which is 1000 times higher than that in traditional reactor. Even when amplifying PP12 into a flat-plate reactor with an area as large as 1 m2 and elongating reaction time to 100 h, H2 bubbling production rate still remains at around 600.0 mmol h-1 m-2, offering a great potential for commercialization.

Development of an Educational Fuel Cell System for Mechanical Engineering Course

Although there is growth in electrochemical system applications such as batteries and fuel cells to power land and air transportation and the current push for hydrogen technology, modeling and control design of thermal and power aspects of such systems is not commonly taught. To incorporate such content, an educational learning hardware system with software interface had been constructed to teach process dynamics and control in selected undergraduate mechanical engineering courses. Given a fuel cell is an energy conversion unit that uses chemical fuel to produce electricity without combustion, a set of student groups developed an educational laboratory system that ensured reliable and consistent power delivery from fuel cell as well as stable hydrogen production using cost-effective and off-the-shelf resources. A 100W Proton Exchange Membrane Fuel Cell (PEMFC) system was constructed through integration of hardware components, and user software interface like MATLAB for accessibility and ease of use in a laboratory course setting. The interface accessed remotely or face-to-face allowed for flow rate, pressure, and temperature measurements to be recorded for student analysis related to understanding of thermal and power performance and management of fuel cell and/or electrolyzer at different operating conditions. The system performed well based on initial testing by a pilot group of other students. It will be implemented in an upcoming course offering related to energy conversion and/or thermal fluid laboratory.

Platinum nanoparticles supported on nickel-molybdenum-oxide for efficient hydrogen production via acidic water electrolysis

A new type of electrode for acidic water electrolysis has been developed, consisting of platinum nanoparticles (Pt NPs) deposited on a nickel-molybdenum-oxide (Ni0.6Mo0.4-oxide) coating. The Pt NPs were synthesized and electrodeposited onto the Ni0.6Mo0.4-oxide support, resulting in platinum nanoparticles deposited on a nickel-molybdenum-oxide coating electrodes (Pt/Ni0.6Mo0.4-oxide) that exhibited exceptional stability for hydrogen production in acidic conditions. Electrochemical testing showed that the Pt40/Ni0.6Mo0.4-oxide electrode had the highest catalytic activity among all catalysts tested, which was comparable to the state-of-the-art Pt catalyst for hydrogen production. Microscopy and spectroscopy techniques were used to characterize the electrode, revealing well-defined Pt NPs firmly attached to the Ni0.6Mo0.4-oxide support catalyst. This increased catalytic activity while reducing the amount of expensive Pt required.

Solar Biomass Reforming and Hydrogen Production with Earth-Abundant Si-Based Photocatalysts.

Efficient electrochemical hydrogen production and biomass refinery are crucial for the decarbonization of various sectors. However, their energy-intensive nature and low efficiency have hindered their practical application. In this study, earth-abundant and non-toxic photocatalysts that can produce hydrogen and reform biomass efficiently, utilizing unlimited solar energy, are presented. The approach involves using low-bandgap Si flakes (SiF) for efficient light-harvesting, followed by modification with Ni-coordinated N-doped graphene quantum dots (Ni-NGQDs) to enable efficient and stable light-driven biomass reforming and hydrogen production. When using kraft lignin as a model biomass, SiF/Ni-NQGDs facilitate record-high hydrogen productivity at 14.2mmolgcat -1 h-1 and vanillin yield of 147.1mgglignin -1 under simulated sunlight without any buffering agent and sacrificial electron donors. SiF/Ni-NQGDs can be readily recycled without any noticeable performance degradation owing to the prevention of deactivation of Si via oxidation. This strategy provides valuable insights into the efficient utilization of solar energy and practical applications of electro-synthesis and biomass refinement.

Steam reforming of ethanol for hydrogen production: Efficacy of ceria promoted Cu–Co on mesoporous cellular foam silica

Mesoporous silica-supported metals are often used as catalysts in the steam reforming of hydrocarbons to produce hydrogen or syngas. In the current study, the steam reforming of ethanol was undertaken using mesoporous cellular foam silica (MCF) and SBA-15 as supports with bimetals Cu and Co in different proportions. Among these 20% Cu–Co (1:1)/MCF was found to be superior exhibiting good activity and stability for hydrogen production. Thereafter, Ce was introduced to reduce coke deposition on the said catalyst. Amongst all synthesized catalysts 5%Ce–10%Cu–10%Co/MCF led to higher hydrogen yield (82.1%) with 97.4% conversion of ethanol at a lower temperature (673 K) using steam to carbon (S/C) ratio of 6. The effect of temperature, GHSV, and S/C ratio on H2 production was systematically examined. Ce-promoted Cu–Co/MCF provided high stability for three cycles, indicating its multi-cycle durability and selectivity. 5%Ce–10%Cu–10%Co/MCF produces hydrogen from ethanol in a sustainable way.

Engineering Amorphous/Crystalline Ru(OH)3/CoFe-Layered Double Hydroxide for Hydrogen Evolution at 1000 mA cm-2.

For large-scale industrial applications, it is highly desirable to create effective, economical electrocatalysts with long-term stability for the hydrogen evolution reaction (HER) at a large current density. Herein, we report a unique motif with crystalline CoFe-layered hydroxide (CoFe-LDH) nanosheets enclosed by amorphous ruthenium hydroxide (a-Ru(OH)3/CoFe-LDH) to realize the efficient hydrogen production at 1000 mA cm-2, with a low overpotential of 178 mV in alkaline media. During the continuous HER process for 40 h at such a large current density, the potential remains almost constant with only slight fluctuations, indicating good long-term stability. The remarkable HER performance can be attributed to the charge redistribution caused by abundant oxygen vacancies in a-Ru(OH)3/CoFe-LDH. The increased electron density of states lowers the charge-transfer resistance and promotes the formation and release of H2 molecules. The water-splitting electrolyzer with a-Ru(OH)3/CoFe-LDH as both an anode and a cathode in 1.0 M KOH demonstrates stable hydrogen production and a 100% faradic efficiency. The design strategy of interface engineering in this work will inspire the design of practical electrocatalysts for water splitting on an industrial scale.

Algal Hydrogen Production and Exopolysaccharide Patterns in Chlorella–Bacillus Inter-Kingdom Co-Cultures

Biohydrogen production from wastewater using eukaryotic green algae can be facilitated by appropriately selected bacterial partners and cultivation conditions. Two Chlorella algal species were chosen for these experiments, based on their robust growth ability in synthetic wastewater. The applied three Bacillus bacterial partners showed active respiration and efficient biomass production in the same synthetic wastewater. Bacillus amyloliquefaciens, Bacillus mycoides, and Bacillus cereus as bacterial partners were shown to specifically promote algal biomass yield. Various inter-kingdom co-culture combinations were investigated for algal–bacterial biomass generation, for co-culture-specific exopolysaccharide patterns, and, primarily, for algal biohydrogen evolution. Chlorella sp. MACC-38 mono- and co-cultures generated significantly higher biomass compared with that of Chlorella sp. MACC-360 mono- and co-cultures, while in terms of hydrogen production, Chlorella sp. MACC-360 co-cultures clearly surpassed their Chlorella sp. MACC-38 counterparts. Imaging studies revealed tight physical interactions between the algal and bacterial partners and revealed the formation of co-culture-specific exopolysaccharides. Efficient bacterial respiration was in clear correlation with algal hydrogen production. Stable and sustainable algal hydrogen production was observed in synthetic wastewater for Chlorella sp. MACC-360 green algae in co-cultures with either Bacillus amyloliquefaciens or Bacillus cereus. The highest algal hydrogen yields (30 mL H2 L−1 d−1) were obtained when Chlorella sp. MACC-360 was co-cultured with Bacillus amyloliquefaciens. Further co-culture-specific algal biomolecules such as co-cultivation-specific exopolysaccharides increase the valorization potential of algal–bacterial co-cultures and might contribute to the feasibility of algal biohydrogen production technologies.

Interfacial molecular regulation of TiO2 for enhanced and stable cocatalyst-free photocatalytic hydrogen production

On the basis of the inherent property limitations of commercial P25-TiO2, many surface interface modification methods have attracted substantial attention for further improving the photocatalytic properties. However, current strategies for designing and modifying efficient photocatalysts (which exhibit complicated manufacturing processes and harsh conditions) are not efficient for production that is low cost, is nontoxic, and exhibits good stability; and therefore restrict practical applications. Herein, a facile and reliable method is reported for in situ amine-containing silane coupling agent functionalization of commercial P25-TiO2 by covalent surface modification for constructing a highly efficient photocatalyst. As a consequence, a high efficiency of H2 evolution was achieved for TiO2-SDA with 0.95 mmol h−1 g−1 (AQE ∼45.6 % at 365 nm) under solar light irradiation without a co-catalyst. The amination modification broadens the light absorption range of the photocatalyst, inhibits the binding of photogenerated carriers, and improves the photocatalytic efficiency; which was verified by photochemical properties and DFT theoretical calculations. This covalent modification method ensures the stability of the photocatalytic reaction. This work provides an approach for molecularly modified photocatalysts to improve photocatalytic performance by covalently modifying small molecules containing amine groups on the photocatalyst surface.

Floatable photocatalytic hydrogel nanocomposites for large-scale solar hydrogen production.

Storing solar energy in chemical bonds aided by heterogeneous photocatalysis is desirable for sustainable energy conversion. Despite recent progress in designing highly active photocatalysts, inefficient solar energy and mass transfer, the instability of catalysts and reverse reactions impede their practical large-scale applications. Here we tackle these challenges by designing a floatable photocatalytic platform constructed from porous elastomer-hydrogel nanocomposites. The nanocomposites at the air-water interface feature efficient light delivery, facile supply of water and instantaneous gas separation. Consequently, a high hydrogen evolution rate of 163 mmol h-1 m-2 can be achieved using Pt/TiO2 cryoaerogel, even without forced convection. When fabricated in an area of 1 m2 and incorporated with economically feasible single-atom Cu/TiO2 photocatalysts, the nanocomposites produce 79.2 ml of hydrogen per day under natural sunlight. Furthermore, long-term stable hydrogen production in seawater and highly turbid water and photoreforming of polyethylene terephthalate demonstrate the potential of the nanocomposites as a commercially viable photocatalytic system.

Alkali functionalized carbon nitride with internal van der Waals heterostructures: Directional charge flow to enhance photocatalytic hydrogen production

Improving the charge separation and migration in graphitic carbon nitride (CN) is the critical issue to enhance its photocatalytic performance, but still remains very challenging. Herein, the alkali metals were introduced into the interlayer and intralayer of CN to tackle this challenge. The lithium sodium-modifying carbon nitride layer (LiNaCN2) and the adjacent CN layer formed a van der Waals heterostructures (VDWHs), while the potassium-intercalating served as interlayer charge transfer channels to induce the directional charge flow. Experiments and theoretical calculations indicated that such unique construction provided intrinsic driving force to obtain the electrons from LiNaCN2 to CN via directional potassium channels. In accordance with the theoretical prediction, a dramatically red-shift of the light absorption feature was achieved for interlayer potassium-intercalating and intralayer lithium sodium-modifying co-functionalized carbon nitride (LiNaCN-K-CN2) to show narrowed bandgap energy of 2.15 eV. This directional charge flow in CN resulted in the rapid transfer of charge carriers in both interlayer as well as intralayer of CN, which reduced the electronic localization as well as extended the π conjugative effect. Consequently, the LiNaCN-K-CN2 displayed stable and remarkable hydrogen production rate of about 2.46 mmol g−1 h−1 with apparent quantum yield (AQY) of about 13.68% at 435 nm, which was 22 folds higher than that of the pristine CN. This finding provides the feasible strategy to precisely tune the directions of charge transfer for high-performance CN-based photocatalysts.

Triptycene-Based Polymer-Incorporated CdxZn1–xS Nanorod with Enhanced Interfacial Charge Transfer for Stable Photocatalytic Hydrogen Production in Seawater

Solar-driven hydrogen (H2) generation from seawater exhibits great economic value in addressing the urgent energy shortage yet faces challenges from the severe salt-deactivation effect, which could result in the consumption of photoinduced charges and decomposition of catalysts. Herein, a triptycene-based polymer was coated on the surface of a CdxZn1-xS nanorod to form a core-shell heterojunction (TCP@CZS) by using the in situ Suzuki reaction for photocatalytic H2 production from water/seawater splitting. The introduction of TCP can provide a large surface area, enrich the active site, and boost charge transfer for the proton reduction reaction. Benefiting from it, optimal TCP@CZS indicated a H2 evolution rate of 93.88 mmol h-1 g-1 with Na2S/Na2SO3 in natural seawater under simulated solar light irradiation, which was 2.2 and 1.1 times higher than that of pure Cd0.6Zn0.4S and that in pure water, respectively. Besides, the apparent quantum efficiency (AQE) of TCP@CZS-3 under 420 nm light irradiation was 22.6% in seawater. This work highlights the feasibility of the triptycene-based porous organic polymer as an efficient catalyst for solar energy conversion in seawater.